It is believed that to consume the flesh of a mermaid, means that you will never show signs of age, and live forever. However, many cannot handle its taste and become demons for eternity. Towa is a woman whose thirst for this flesh consumes her, as she was made only partially immortal by drinking the blood of a mermaid years ago. Unable to cast her demons aside, she destroys everything in her path on a search for this legend.
Following in the footsteps of Mermaid Forest (another OVA by Rumiko Takahashi), Yuta and Mana are back, and have travelled to a new city for work and rest. By chance, they meet Masato: a young boy whose mother is known to have come back from the dead. The pair discover that Masato's household contains dark secrets, which may end up costing them their lives!
At Count D's pet shop, you can acquire any form of animal, from an ordinary canary, to more.. "exotic" creatures. Made to sign a contract before purchase, Count D claims no "responsibility for actions incurred" if the purchaser does not follow its instructions completely, as results can be fatal. Patrons of this shop are able to get the rarest of creatures, but often, their purchases are coupled with demons from their past that won't go away easily.
Momosuke is a young man with a dream: to travel Japan and collect one hundred stories. He journeys from place to place, searching for tales of the paranormal and bizarre, hoping to collect tales to publish in his book. However, the calm of Momosuke's life soon is shattered by a chance meeting with three sinister beings: Mataichi the priest, Nagamimi the bird-caller, and the beautiful Ogin. Soon, Momosuke learns that there might be more to his newfound comrades than first meets the eye...
Legend says that if the flesh of a mermaid is consumed, the body becomes immortal. However, with the small chance of immortality comes a high chance of being poisoned, morphing and mutating into a monster beyond comprehension. Yuta is a wanderer: one of the few who has eaten the flesh and survived, and lived to tell about it -- for 500 years. By chance, Yuta meets a young woman named Mana who also shares the same fate, and together, they wander the land, searching for a mermaid who can free them from their immortal lives.
Beware the world of the supernatural, for their tricks and secrets will terrify and potentially even kill you. Two groups of girls experience the horror of the unknown in two very different ways: Masami has begun to have terrible nightmares after the arrival of a new transfer student, and a separate group decides to enter a haunted mansion alone at night. Their lives will be inexplicably changed forever once they discover the truth behind these strange events...
It was a tough decision to recommend Mermaid Forest (OVA) or its TV counterpart, but I think the OVA is more appropriate. Both OVAs are short, older and are perfect horror titles to pick up if that's what you're in the mood for. There's twists and turns in both and a good amount of violence - definitely fans of one would appreciate the other.